Evidence-based guidelines emphasize that adequate management of osteoarthritis (OA) requires a combination of medical and behavioral modalities. However, many of the recommended guidelines are not regularly incorporated into clinical practice, and the recommended behavioral strategies (e.g. exercise and weight management) are not practiced by most patients. The objective of this study is to compare a patient- based behavioral intervention, a provider-based intervention, and a combination of the two interventions, for improving outcomes among patients with OA. This study will provide novel, valuable information comparing the impact and cost-effectiveness of these three interventions in the context of real-world primary care settings. This will be a randomized controlled trial of n=560 patients with symptomatic knee or hip OA, using a 2 x 2 factorial design. Patients will be assigned to one of four study arms: 1.) Patient Behavioral Intervention for OA Only, 2.) Provider Intervention for OA Only, 3.) Patient Behavioral Intervention + Provider Intervention for OA, and 4.) Usual Care Control. The Patient Behavioral Intervention will be a twelve-month program that includes the following elements: written educational materials (focused on exercise, weight management, and cognitive behavioral pain management), an exercise video tailored for patients with lower extremity OA, and monthly telephone calls by a counselor to support behavior change. The Provider Intervention will involve giving information on patients' OA symptoms and treatment, as well as patient-specific evidence-based recommendations for care. Providers will have access to this information at the point of clinical care. The primary time point for outcome assessment will be at 12-months. We will also assess a limited set of outcomes via telephone at 6-months, 18-months, and 24-months. The primary outcome will be the Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC). Secondary outcomes will include objective physical function (Short Physical Performance Test) and depressive symptoms (Beck Depression Inventory). The main study analyses will compare outcomes in each intervention group to the usual care control group. We will also assess the cost-effectiveness of each intervention. PUBLIC HEALTH RELEVANCE: Osteoarthritis (OA) is one of the most common chronic conditions and a leading cause of disability among adults. Many patients with OA have significant pain and functional limitations, even though they receive some medical care for their OA. This study will compare an intervention for patients, an intervention for health care providers, and a combination of both interventions for improving pain and function among patients with OA.